Constitutional Court judges cease work after court house is blocked by President Morsi's supporters ahead of key ruling.

Egypt's Supreme Constitutional Court has shelved its work indefinitely after protests by President Mohamed Morsi's supporters outside its headquarters prevented judges from meeting.

"The court registers its deep regret and pain at the methods of psychological assassination of its judges"

- Egypt's Supreme Constitutional Court

"[The judges] announce the suspension of the court sessions until the time when they can continue their message and rulings in cases without any psychological and material pressures," the court said in a statement on Sunday.

"The court registers its deep regret and pain at the methods of psychological assassination of its judges," it said.

The top court had earlier announced it had postponed its ruling on the legitimacy of the constituent assembly, citing "administrative'' reasons.

It is not known whether a new date has been set for the ruling.

Any ruling from the court would be a direct challenge to Morsi - who last month gave himself near absolute powers, placing himself and the assembly above any oversight, including by the judiciary - and could further undermine the charter's legitimacy.

Public referendum

Meanwhile, anti-Morsi protesters continued to occupy Cairo's Tahrir Square on Sunday morning, a day after the president called for a December 15 public referendum on a draft constitution after receiving a copy of the document.

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He called for the vote in a speech on Saturday night before members of the constituent assembly, the 100-member panel that drafted the controversial document.

Morsi is accused by his detractors of usurping sweeping powers and pushing his Muslim Brotherhood agenda in drawing up the draft constitution.

Judges have threatened to boycott observing the referendum, and the secular opposition promised a civil disobedience campaign.

Al Jazeera's Rawya Rageh, reporting from Cairo, said that the constituent assembly was "immunised by this presidential decree".

"But remember the constituent assembly itself rushed through the vote on the draft constitution in a marathon session that lasted for 17 hours, and effectively it becomes dissolved after they put forward this draft constitution," she said.

The presidency has been locked in a power struggle with the judiciary and secular and Christian activists since November 22, when Morsi granted himself wide-ranging power to issue decrees which would not be subject to judicial review.